رأس الغول vs الجدي
Intrinsic output is the great divide here. الجدي carries an absolute magnitude of −3.64 to −0.11 for رأس الغول, near 26 times the true luminosity. رأس الغول trails in apparent brightness at magnitude +2.09 against +1.97, leaving الجدي around 1.1 times the brighter target. الجدي is an F-type star, while رأس الغول is a B-type star in Perseus. الجدي is the remoter of the pair at 433 light-years, roughly 4.8 times the 89.9 that separates us from رأس الغول.
Property comparison
| Property | رأس الغول | الجدي |
|---|---|---|
| التسمية | 26Bet Per | 1Alp UMi |
| الكوكبة | Perseus | N/A |
| النوع الطيفي | Class B — B-type (Blue-White) | Class F — F-type (Yellow-White) |
| القدر الظاهري | +2.09 | +1.97 |
| القدر المطلق | -0.11 | -3.64 |
| المسافة | 89.9 ly | 433 ly |
| الكتلة | N/A | N/A |
| نصف القطر | N/A | N/A |
| درجة الحرارة | N/A | N/A |
| السطوع | N/A | N/A |
Full data for each star: رأس الغول · الجدي
Key differences
Key Differences
- ◆ Both are variable stars, but of different physical types.
- ◆ Polaris is a Cepheid variable that pulsates in radius; Algol dims because a companion eclipses it.
- ◆ Polaris's pulsation amplitude has been decreasing over the past century.
- ◆ Algol varies every 2.87 days (eclipsing); Polaris has a period of about 3.97 days (pulsation).
- ◆ Polaris is near the north celestial pole and vital for navigation; Algol is in Perseus and known as the Demon Star.